Java 中的字节缓冲分配()方法，示例
原文:https://www . geeksforgeeks . org/bytebuffer-allocate-method-in-Java-with-examples/
java.nio.ByteBuffer 类的 allocate() 方法用于分配一个新的字节缓冲区。
新缓冲区的位置将为零，其限制将是其容量，其标记将是未定义的，并且其每个元素将被初始化为零。它将有一个后备数组，并且它的数组偏移量为零。
语法:
public static ByteBuffer allocate(int capacity)
参数:该方法以容量为参数，以字节为单位。
返回值:这个方法返回新的字节缓冲区。
抛出:这个方法抛出 IllegalArgumentException ，如果容量是负整数
下面是说明 allocate()方法的示例:
实施例 1:
// Java program to demonstrate
// allocate() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the ByteBuffer
int capacity = 4;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting the int to byte typecast value
// in ByteBuffer using putInt() method
bb.put((byte)20);
bb.put((byte)30);
bb.put((byte)40);
bb.put((byte)50);
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("ReadOnlyBufferException catched");
}
}
}
Output:
Original ByteBuffer: [20, 30, 40, 50]
实施例 2:
// Java program to demonstrate
// allocate() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity with negative
// value of the ByteBuffer
int capacity = -4;
// Creating the ByteBuffer
try {
// creating object of ByteBuffer
// and allocating size capacity
System.out.println("Trying to allocate negative"+
" value in ByteBuffer");
ByteBuffer bb = ByteBuffer.allocate(capacity);
// putting int to byte typecast value
// in ByteBuffer using putInt() method
bb.put((byte)20);
bb.put((byte)30);
bb.put((byte)40);
bb.put((byte)50);
bb.rewind();
// print the ByteBuffer
System.out.println("Original ByteBuffer: "
+ Arrays.toString(bb.array()));
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
Trying to allocate negative value in ByteBuffer
Exception thrown : java.lang.IllegalArgumentException
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